1. Technical Field of the Invention
The present invention relates to a semiconductor device in which a semiconductor chip such as a chip size package or a flip chip is provided with a heat spreader for radiation of heat and the method of manufacturing the same.
2. Description of the Related Art
In recent years, in the multimedia society, accompanying with rapid increment of an information amount and development of an electronic equipment, high integration and high-speed of an electronic component are proceeded and at the same time, miniaturization of a semiconductor device is proceeded, and then miniaturization of a chip size package (hereinafter, referred as CSP) which has the nearly same size as a semiconductor chip and a flip chip (hereinafter, referred as FC) is proceeded.
However, according to high densification of a semiconductor device in recent years, heat generation in the operation becomes increased, thereby, in order to suppress the generation of heat of the semiconductor device, an essential improvement such as decrease of an operating voltage and design for decreasing a current loss is required. At the same time, a counterplan has been performed in which a fan is provided to forcibly cool the semiconductor device or a heat spreader for radiation of heat and a radiating fin are provided.
FIGS. 1A to 1D show methods for providing a heat spreader in a conventional FC in the process sequence.
First, as shown in FIG. 1A, a FC product 100 is fixed to a predetermined position on a working table 101.
Then, as shown in FIG. 1B, an Ag paste 103 stored in a syringe 102 is dropped and applied to the FC product 100 by a predetermined amount. At this time, according to the shape of the heat spreader to be mounted later, the position for applying the Ag paste 103 and the number of the applications (dropping) become different.
Then, as shown in FIG. 1C, the FC product 100 applied with the Ag paste 103 is mounted to a thermal bonding tool 104 of a thermal bonding apparatus. Also, a heat spreader 106 or a heat spreader attached with a support ring is mounted on a heat table 105. The heat spreader 106 is made of aluminum, copper or alloy thereof.
Subsequently, as shown in FIG. 1D, the FC product 100 is tightly pressed to the heat spreader 106 heated by the heat table 105 by the thermal bonding tool 104, the Ag paste 103 is heated and pressed to be cured, and the FC product 100 and the heat spreader 106 are heated and compressed. Thereby, the heat spreader 106 composed of aluminum, copper, or alloy thereof is attached to the FC product 100.
However, since the difference of thermal expansive coefficient between the heat spreader 106 and the semiconductor chip (the FC product 100) is large, a stress generated between the heat spreader 106 and the semiconductor chip can be relaxed in order to directly attach the heat spreader 106 composed of aluminum, copper, or alloy thereof with an excellent heat radiation property to the semiconductor chip, and moreover, an adhesive which has a heat resistance, an electrolytic corrosion resistance and a moisture proof and has less deterioration in case that the moisture proof test is performed under the strict condition such as, particularly, the PCT (Press Cooker Test) process is required. However, a liquid adhesive has a problem that attention to the preservation stability of the adhesive must be paid and a problem that the operating efficiency is deteriorated in comparison with a LOC (Lead On Chip). Also, since a silver paste has a problem that a silver filler is precipitated, there is a problem that dispersion of the silver filler is not uniformed.
Also, as problems related to the process, in case the thermal bonding method, since the semiconductor chip and the heat spreader are bonded with large load of several tens kg, the thermal boding tool 104 often gives damages to the semiconductor chip. Particularly, in case that the thermal bonding tool 104 is contacted to a solder resist layer of the semiconductor chip surface, there is a problem that stripping of the solder resist layer is easily occurred.
Also, in case that the support ring is connected to the heat spreader, since the area of the support ring is large, the time for the thermal bond is needed, and then there is a difficulty that the index time for the process is long. And, since the Ag paste is used, there is a defect that the cost is expensive.
Thus, the object of the present invention is to provide a method of manufacturing a semiconductor device which is not subjected to restriction by a stress due to the difference of thermal expansive coefficient between a heat spreader and a semiconductor chip, does not need to consider preservation stability of an adhesive and an uniform dispersion of a filler, does not need a thermal bonding tool to avoid damages of the semiconductor chip due to that, and accomplishes the quickness of the process time.
A semiconductor device having a heat spreader attached thereto according to a first aspect of the present invention comprises a substrate; a semiconductor chip mounted on the substrate; an insulating resin layer for sealing the side of the semiconductor chip on said substrate; and a copper paste film contacted to the exposed surface of the surface of said semiconductor chip, wherein said copper paste film functions as a heat spreader.
A semiconductor device having a heat spreader attached thereto according to a second aspect of the present invention comprises a semiconductor chip; and a copper paste film formed to be contacted to the surface of the semiconductor chip, on which a wiring is not formed. Said copper paste film is cut and separated at the same time when said semiconductor chips are individually divided from a semiconductor wafer. Said copper paste film functions as a heat spreader.
In the semiconductor device having a heat spreader attached thereto of the first and the second aspects of the present invention, said copper paste film is formed by applying a copper paste, or said copper paste film is supplied as a copper paste film coated on a sheet base material.
Also, said copper paste film has irregularities on the surface to which said semiconductor chip is not contacted, to extend the radiation area.
A method of manufacturing a semiconductor device having a heat spreader attached thereto according to a third aspect of the present invention comprises the steps of mounting a plurality of semiconductor chips on a substrate; sealing said substrate between said semiconductor chips with an insulating resin; and forming a copper paste film as a heat spreader on the exposed surface of said semiconductor chip and on said insulating resin.
A method of manufacturing a semiconductor device having a heat spreader attached thereto according to a fourth aspect of the present invention comprises the steps of forming a copper paste film as a heat spreader on the surface of said semiconductor wafer, on which a wiring layer is not formed, said semiconductor wafer having said wiring layer on other surface and a semiconductor element; and dividing said semiconductor wafer into a plurality of individual chips, thereby, at the same time, separating said copper paste film into individual copper films on the semiconductor chips.
In the method of manufacturing a semiconductor device having a heat spreader attached thereto of the third aspect of the present invention, said substrate is a multi-layer wiring substrate and a gap between said semiconductor chip and said multi-layer wiring substrate is sealed with the insulating resin in said step of mounting the semiconductor chips. Also, the steps of sealing said substrate between said semiconductor chips with the insulating resin includes supplying the insulating resin to a gap between said semiconductor chips by using capillary phenomenon, supplying the insulating resin by injection, or supplying the insulating resin by transfer. Also, the steps of curing said copper paste film so as to be solidified after said copper paste film is formed, and individually dividing said semiconductor chips together with said copper paste film are provided.
Also, in the third and fourth aspects of the present invention, in the step of forming said copper paste film, said copper paste film can be supplied by dropping and applying of the copper paste or in the step of forming said copper paste film, said copper paste film can be supplied by the copper paste applied on the sheet base material.
In the present invention, the heat spreader has the copper paste film formed on to be contacted to the semiconductor chip. The copper paste film is inexpensive in the material cost, the process thereof is easy, and heat radiation property of the semiconductor chip can be improved by the low cost. Also, the copper paste film is not precipitated as like the Ag filler, and the treatment is easy.
Also, in the present invention, since the copper paste film itself on the semiconductor chip functions as a heat spreader, the heat spreader of different component needs not be compressed by using the thermal bonding tool on the semiconductor chip, damages of the semiconductor chip in the thermal bonding process can be avoided, and at the same time, the processing time can be reduced.